FSAA: Need for Speed

We have found out above that Nvidia GeForce 7950 GX2 has more options when it comes to antialiasing and that its 8x and higher modes offer generally higher image quality compared to ATI’s 6x. However, the quality should always be considered in conjunction to the “quantity” of frames per second.

In order to find out which FSAA modes are actually suitable from the speed point of view in the latest games, we decided to benchmark Half Life 2: Episode One as well as Elder Scrolls: Oblivion with different FSAA settings.

Half-Life 2: Episode 1

It is interesting to note that full-scene antialiasing is virtually free in Half-Life 2: Episode 1 in 1280x1024 resolution. In higher resolutions FSAA does reduce performance, but not dramatically. Even in 1920x1200 you will be able to play comfortably with 4x AA and high-quality angle-independent anisotropic filtering on the Radeon X1950 XTX. Obviously, the GeForce 7950 GX2 is a little bit faster, but it does not offer angle-independent AF, which is noticeable in certain cases.

Obviously, ATI’s 6x FSAA mode is a lot faster than the rest and it is hard do say that such a significant performance delta results in significant image quality difference. Nevertheless, it should be noted that both 8x and 8xs modes can be used in 1280x1024 and the former even manages to showcase nearly decent performance in 1600x1200! Unfortunately, performance with 16xs enabled is too low to consider it seriously for first person shooters.

Elder Scrolls: Oblivion

Speaking generally and considering the results above, we can notice that there is practically no speed difference for situations with and without FSAA in the “indoor” levels of Elder Scrolls: Oblivion , which may be conditioned by the fact that performance is mainly limited by pixel shader performance, rather than memory bandwidth or the number of ROPs.

Advanced FSAA modes cannot boast with really good performance in any resolution, even though, considering nature of the title, we would suggest that up to 8xs modes can be used in 1600x1200 in the “indoor” cases of the game.

Considering the fact that modern hardware cannot provide really good performance in outdoor levels of Oblivion game, we cannot really recommend using FSAA at all, except for lower resolutions.

With the numbers above, we do not think it makes any sense to use 6x FSAA or higher in the current case.

Let’s summarize the performance graphs above:

• ATI’s 6x FSAA is a nice balance between speed and quality, even though it cannot be used in many cases.
• Nvidia’s 8x and 8xs modes are not as fast at ATI’s 6x, however, it looks like in cases where they cannot be used, the 6x is also not a really good performer.
• Nvidia’s 16xs FSAA is inferior performer in modern games. It cannot be used anywhere due to dramatic performance drop.